Fuel burning apparatus



July 30, 1957 E. c. MILLER ErAL 2,800,888

FUEL BURNING APPARATUS.

2 Sheets-Sheet l Filed Dec. 30, 1953 [ARLE C. M/LLER OL L/.so/v CRA/qmmm/MW ATTORNEY July 30, 1957 E, c, MILLER ETAL 2,800,888

FUEL BURNING APPARATUS 2 Sheets-Sheet 2 Filed Deo. 30, 1953 E meaFWalmmm Mc .N O L E0 www ATTORNEY United States Patent FUEL BURNINGAPPARATUS Earle C. Miller and llison Craig, Worcester, Mass., as-

sgnors to Riley Stoker Corporation, Worcester', Mass., a corporation ofMassachusetts Application December 30, 1953, Serial No. 401,158

2 Claims. (Cl. 122-479) This invention relates to fuel burning apparatusand more particularly to apparatus arranged to be used with a steamgenerating unit.

In the past it has been a common practice to provide for the control ofsuperheat in a steam generating unit by controlling the angle to thehorizontal of the flame produced by the burners in the furnace serving aboiler. By the use of a directional flame burner it is possible toprovide for a considerable range of superheat temperature by adjustmentof the flame from an extreme downward position in the furnace to anextreme upward position in the furnace. The selection of variouspositions of the directional flame burner to provide a desired superheattemperature is accompanied by certain disadvantages. One of thesedisadvantages is that the temperature in the lower portion of thefurnace is changed at the same time that the angle of the burner ischanged and this results in varying degrees of slagging. It can beunderstood that, when the burner is directed in an extreme upwardposition, there is a tendency to set up conditions in the lower portionof the furnace which do not permit ease of ow of slag. At the same time,a definite position of a burner in a furnace may be selected to obtaincomplete or almost complete combustion. However, when the ame positionis changed to control superheat, the degree of combustion may alsochange, resulting in excessive fiyash, particularly in the case ofpulverized coal. By use of the present invention it is possible toobviate some of these diicultics while at the same time obtaining adesirable degree of control of superheat.

It is therefore an outstanding object of the present invention toprovide an apparatus for burning fuel which will permit a wide range ofcontrol of superheat and at the same time bring about the optimum amountof slagging in the lower portion of the furnace.

It is another object of the present invention to provide a fuel burningapparatus in which the waste of unburned carbon in yash is minimized.

A still further object of the present invention is the provision of afuel burning apparatus which provides for the control of superheat andat the same time permits the complete burning out of carbon from yashand the maintenance of optimum slagging conditions.

A still further object of this invention'is the provision of fuelburning apparatus for maintaining a slag pool in an optimum conditionand for the disposal of yash along with the slag.

Another object of the invention is the provision of apparatus for use inthe burning of pulverized coal in a furnace of the slag-pool type,wherein provision is made for the control of superheat and themaintenance of optimum slagging conditions as well as complete disposalof yash.

Although the novel features which are believed to be characteristic ofthis invention will be particularly pointed out in the claims appendedhereto, the invention itself as to its objects and advantages, the modeof its operation,

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and the manner of its organization may be better understood by referringto the accompanying description taken in connection with theaccompanying drawings forming a part thereof, in which Figure l is alongitudinal sectional view of a steam generating unit constructed afterthe teaching of the present invention, and

Figure 2 is an enlarged longitudinal view of a burner embodying theprinciples of the invention.

Like reference characters denote similar parts in the several figures ofthe drawings.

Referring first to Figure l, wherein is best shown the general aspectsof the invention, a steam generating unit, designated generally by thereference character 10, is shown as comprising a boiler 11 and a furnace12. The furnace 12 is made up of a forward wall 13, a rear Wall 14, andside walls 15 dening a combustion chamber 16. A refractory basin 17forms the lower portion of the furnace in which a slag pool may bemaintained. Suitable provision, not shown, is provided for tapping theslag pool in the usual manner. The boiler 11 comprises in the usual waya steam-and-water-drum 18, a mud drum 19, downcomer tubes 20, andsteaming tubes 21. A convection superheater 22 is connected on its inletend to the steam-and-water-drum 18, and at its outlet end to a header 23from which it is carried to turbines not shown. Below the tube banks ofthe boiler is situated a yash-collecting hopper 24. A breaching 25 ofthe usual type is connected to an induced draft fan 26 to which is alsoconnected a cyclone-type'yash separator 27 for cleaning the gases beforeprojecting them into a chimney, not shown. A conduit 28 is connected tothe lower portion of the hopper 24, while a conduit 29 extendsdownwardly from the tlyash collector 27 Conduits 28 and 29 are connectedto a yash conduit 30 in which resides an ejector 31 provided withpressure air by a fan 32. In the front wall 13 of the furnace l2 issituated a burner 33 which will be described more fully hereinafter. Theburner 33 is provided with heated secondary air from the air heater 25.It is also provided with flyash through the conduit 30. A coal bunker 34sends coal down a chute 35 and through a feeder 36 into a coalpulverizer 37. The outlet of the coal pulverizer is connected to theburner through a conduit 38. As is evident in the drawings, the burner33 comprises a set of upper directing vanes 39 and a set of lowerdirecting vanes 40. A temperature indicating means 41 resides in thesuperheated steam header 23 and is connected by a lead 42 to acontroller 43. The controller 43 in turn sends a signal through leads 44to a motor 45 which actuates the upper directing vanes 39 in a mannerwhich will be described more fully hereinafter. This superheat controlmeans may be either electrical or hydraulic.

Referring next to Figure 2 wherein are best Ishown the details of theburner 33, it can be seen that the upper directing vanes 39 and thelower directing vanes 40 are independently adjustable and controllable.All the vanes, however, are of an elongated, diamond-shaped crosssectionand are mounted on a horizontal pivot 46 passing generally through thecenter of gravity of the cross-sec# tion. The upper directing vanes 39are connected by links 47 to an actuating shaft 48 which is in turnconnected to the motor 45 for the actuation thereof. The lower directingvanes 40 are connected by links 49 to an actuating shaft 50, the outerextremity of which is threaded at 51 and is provided with a hand wheel52. The threaded portion 51 passes through a fixed nut 53, whereby theactuating shaft 50 may be moved longitudinally, thus changing theangularity of the directing vanes 40. The vanes are enclosed by ahousing 54 which flares outwardly toward the furnace. An ignition torch55 of the usualtype is provided Ycentrally of the burner. On

either side ofthe torchand horizontally thereof isa large 57 connectedto the flyash conduit Si). The nozzle openingv is directed-toward thevanes; thatis to say, 'downstream of theilow-of fuel and air. Y

TheV outer portion of the burner comprises a fuel tube 58 which isconnected at itsrouter end to 'a fuel distributing head 59 whoseinlet-is'connectedj to thepulverized coal' conduit @3Sconnectedtothe-pulverizer37. Theusual adjustablevanes 6l) are providedfor controlling'coal'distrihution Within the tube'SS. TheLinner vend ofthe tube 58' is provi'ded'with` fuelgspreading vanes 6l in the usualway. `Surrounding the tube 58 is a :secondary air housing 62'whoseentranceisprovided with adjustable vanes 63 for controllingtl'le'entrance of hot sccondaryair originating in the ',air'heater 25.The Yvaries 63 Vare adjustable through a linkage-mechanism 64 and a handcrank 65. Alsuitableair directing tube 66 and mixing vanes 67 are also'provided.

The operationof the apparatus will now be understood in view of theabove description. Feedwater is introduced nearthe steam-and-water-drum18, passes downwardly through the downcomer tubes 20, and, aftercirculating through the tubes of the boiler, passes upwardly into thespace over theY water in the steam-and-water-drum and passesl intothevsuperheater 422. The superheated steam leaves the superheater, entersthe header 23, and passes eventually to the turbines. The temperature ofthe superheated steam is measured bythe indicator 4l and aproportionate'signal is transmitted through the lead 42 to the `heatedby' the air heater 25 passes Vto the burner 33 by means of the'housing62. VFuel leaving the bunker 34 passes downwardly through the chute 35Vthrough Lthe feeder 36 and is reduced to a powder in the pulverizer 37.The'pulverized coal 'leaves through the conduit 38 and enters .thedistributinghead 59. Pulverized coal and air are mixed by the-vanes'67and pass into the burner housing 54. The mixed fuel and air is split bythe central dividing vane S6 into an upper and a lower component. Thedirection of the flame produced by the burning of the upper component iscontrolled by the upper directing vanes 39, Whiletheiarne produced bythe lower component is controlled by the lower directing vanes 40. Asthe operation of thetstearn. generating unit progresses, the controllerY43 will receive signals from the indicator 41 indicative of thesuperheat temperature being obtained and willV adjust the vanes '39toproducey a 'change in superheat temperature, if such be necessary.Slag forming on the walls of the combustion chamber 16 will passdownwardlyy to the refractory basin`17 and will collect, forming a slagpool. In order Vthat this slag pool may remain inthe Vproper viscosityfor tapping, the .operator is able to direct the ameformed by'the vanes'dil in the proper direction to maintain the desired slag condition. Hedoes this by actuation of the wheelf52, thereby changing the angularityof the vanes 4G through the threaded portion 5l, the actuat-Y ing shaft50, and the links 49. VAt the same time yash originating in the hopper24 and the separator 27 falls' down the respective conduits 28 and 29into the flyash conduit 30. VThe yash is propelled under the action ofthe fan 32 and the ejector 31 and passes into the burner housing 54through the nozzle 57. Since the nozzle is situated in the lower portionof the burner, the flyash will take the direction dictated bythe'vanes'40fand-willfreside in the lower llameV controlled by the Vanes40 and will be projected in a downward direction toward the slag pool.The carbon remaining in the flyash will be completely burned out in thehot llame and the remaining yash will be caught in the sticky slagpool.The yash will thus be j completely burned out and disposed of.

controller 43. Gas originating in the combustion chamber Y `i6passesrthrough the furnace ove'r the steaming tubes,

Y also prevent the flyash striking the slag pool.

As is evident from the above, thereeare' distinct advantages in mixingthe ilyash, coal, Yande-air in the burner and'.

air high in oxygen, thus promoting complete combustion of the iiyash.

While certain novel features ofV theinventifon have beenV shown an'ddescribed and are pointed out inthe annexed claims, it will beunderstood that various omissions, sub-V stitutions, and changes in theforms and details of the device-illustrated and in its operation may bemade by those skilled in the art ywithout departing from the spirit ofthev invention. e

Having thus described our invention, whatwe claim as new and desire tosecure by LettersPatent is:

1.7A fuel burningapparatus comprising a pulverized coal red steamgenerating Aunit having a convection superheater and a refractoryslag-basin, a burner havingV provision for directing aV portion of theflame in'ran upward direction and controlling'the Aangle to thehorizontal occupied by the said portion, the burner also having aprovision locatedjust above the basin for directing the remainingportion of the arne in a downward direction into the basinandcontrolling the angle to the horizontal occupied by the said remainingportion, means Vfor-injectinglllyash into thes'aid remaining portionAonly of the llame, `and means responsive to the temperature ofthe steamleaving the superheater to actuate the burner to change the angle of theupwardly directed portion of the flame to cause the said temperature t-ochange to a desired level.

2. A fuel burning apparatus comprising a pulverized coal-tired steamgenerated unit having a convection superheater and refractory slagbasin, a burner having provision including horizontally-.pivoted vanesfor directing a portion of the ilame in an upward direction andcontrolling the angle to the horizontal `occupied by the said'portion,the boiler also having a provision including horizontallypivoted vaneslocated just above the basin for directing the remaining portion of thellame in a downward direction into the basin and controlling theangle'to the horizontal occupied by the said remaining portion, meansforinjecting tlyash into the said remaining portion only of the llame, andmeans responsive to the temperature of the steam leaving the(superheaterYto-actuate the burner to change'the angle of theupwardly-directed portion of the ame to cause the` said temperature tochange to a desired level.

References Cited in the tileofV this vpatent UNITED. STATES PATENTS,Frisch Jan. 21, 1941

